Melanoma within naevus spilus: 5 cases

BACKGROUND: Nevus spilus is defined as café-au-lait macules with dark maculopapular speckles. Histologically, it has the aspect of lentigo associated with nevocellular nevus. There are 3 types of nevus spilus: small or medium-sized (<20 cm), giant and zosteriform. Malignant transformation of nevus spilus is rare. PATIENTS AND METHODS: We analyzed the cases of 5 patients presenting melanoma within nevus spilus as well as 20 published cases. The evaluation criteria were: for nevus spilus: size, type, topography, age of onset and presence of dysplastic nevi within the nevus spilus; for melanoma: clinical aspect, histological type, thickness, level and age at diagnosis. The presence of other risk factors for melanoma was noted. RESULTS: The 14 women and 11 men had a mean age of 49 years at melanoma diagnosis. Type of nevus spilus was: small or medium-sized (15 cases), zosteriform (6 cases) and giant (4 cases). Only 3 nevi spili were<4 cm in diameter. Nevus spilus was present since birth (11 cases), childhood (7 cases), after the age of 20 years (3 cases) and was unspecified in 4 cases. Three of our five patients had other risk factors for melanoma. Two patients were presenting 2 melanomas within nevus spilus. The histological type of melanoma was not specified in 8 cases but SSM was the most common type (13 cases). Median Breslow thickness was 1.25 mm (0.27 to 8 mm) for the 19 cases in which it was specified. CONCLUSION: The following criteria appeared to be associated with risk of developing melanoma in nevus spilus patients: nevus spilus present since birth, nevus spilus over 4 cm in diameter, and giant or zosteriform nevus spilus. Development of melanoma within nevus spilus is a rare event. Consequently, guidelines for follow-up of nevus spilus cannot be defined. However, follow-up is recommended, and in particular, self-examination.